Homestake Mine — 126 Years, 40 Million Ounces, Deepest in the West

The Black Hills gold rush began with General Custer's 1874 expedition — a violation of the 1868 Fort Laramie Treaty that guaranteed the Hills to the Lakota Sioux. When soldiers in Custer's column confirmed gold in the creeks, the US government found it impossible to keep prospectors out. Within two years 15,000 miners had flooded the Black Hills. The resulting conflict helped trigger the Great Sioux War of 1876 and the Battle of Little Bighorn.

Manuel and Fred Brothers found the rich quartz vein that became the Homestake in April 1876. They quickly sold it — as so many finders do — to California investors including George Hearst, the father of newspaper magnate William Randolph Hearst. Hearst paid $70,000 and received $400 million over his lifetime. The mine funded the Hearst family dynasty.

The Deepest Mine in the Western Hemisphere

By the time it closed in 2002, Homestake's main shaft reached 8,000 feet below surface — more than a mile and a half deep. At those depths, the rock temperature reaches 130°F and drilling creates fine silica dust that destroys lungs (silicosis). Homestake pioneered the dry drilling techniques and ventilation systems that became the global standard for deep hard-rock mines.

After the Mine: Physics Goes Underground

The emptied mine shafts turned out to be perfect for something else entirely: deep underground physics experiments requiring shielding from cosmic rays. The Sanford Underground Research Facility now operates in the old Homestake workings, housing experiments studying dark matter, neutrinos, and other fundamental physics questions.